I can share folders between Mac (OS 9, OS X) and PC (Win 98, 2000, XP pro) on our network using both AppleShare and SMB on SAMBA.

What I want to do is enable network login on the Mac's using OS X so that we can use the usernames we have created at the SAMBA-server instead of creating the users on each Mac (or - as we do for the moment - having the Mac's auto-login).